Dashpot with two cylinders

ABSTRACT

A dashpot with an inner cylinder ( 3 ) accommodated in an outer cylinder ( 1 ), and a piston ( 6 ) traveling back and forth inside on the end of a piston rod ( 5 ) and separating the inner cylinder into two chambers ( 7  &amp;  8 ). The piston rod enters the cylinders through a hole at one end that seals it off and positions it. The outer cylinder is provided with a base ( 4 ) at the end opposite the end with the hole. The inner cylinder is centered along the axis of the outer cylinder at each end. The cylindrical gap ( 2 ) between the two cylinders is provided with a fluid-accommodating compartment ( 11 ) and, toward the base, a port ( 13 ) opening into the adjacent chamber ( 8 ). The chamber accommodates, preferably above the port, a vent ( 12 ). The mutually contacting ends of the cylinders are hot or cold welded together at the base end or at the end remote from the base.

LIST OF PARTS

[0001]1. outer cylinder

[0002]2. cylindrical gap

[0003]3. inner cylinder

[0004]4. base

[0005]5. piston rod

[0006]6. piston

[0007]7. chamber

[0008]8. chamber

[0009]9. open end

[0010]10. packing

[0011]11. compartment

[0012]12. vent

[0013]13. port

[0014]14. ports

[0015]15. depression

[0016]16. screw

[0017]17. inward-tapering section

[0018]18. collar

[0019]19. port

[0020]20. lower end

[0021]21. depression

[0022] The present invention concerns a dashpot with two cylinders.

[0023] Two-cylinder dashpots of this genus are preferred for eliminatingthe vibrations that occur between a vehicle and its wheels. Suchabsorbers generally comprise two loosely concentric cylinders, the gapbetween them occupied by a cushion of gas that compresses to accommodatethe gas forced in by a piston rod that slides in and out to variousextents.

[0024] The base of the outer cylinder in a dashpot disclosed in GermanOS 1 750 679 is molded on. That of the outer cylinder disclosed in WO97/16656 on the other hand is separate and welded, cemented, or solderedon.

[0025] Both embodiments have the drawback that precisely centering theinner cylinder in relation to the outer cylinder requires considerablecare.

[0026] The object of the present invention is accordingly a simple andreliable means of attaching the outer cylinder to the inner cylinder ofsuch a dashpot.

[0027] This object is attained in accordance with the present inventionin a dashpot of the aforesaid genus by the characteristics recited inthe body of claim 1. Advantageous additional and advanced embodimentsare addressed by claims 2 through 5.

[0028] The major advantage of the present invention is that the outercylinder is reliably secured to the inner cylinder. Furthermore,however, the means of attachment are simple, which considerablydecreases the cost of manufacture.

[0029] One embodiment of the present invention will now be specifiedwith respect to the accompanying drawing, wherein

[0030]FIG. 1 is a section through a dashpot with two cylinders,

[0031]FIG. 2 illustrates another version of the dashpot,

[0032]FIG. 3 is a larger-scale illustration of the base of a dashpot,and

[0033]FIG. 4 illustrates another version of the base illustrated in FIG.3.

[0034] A dashpot comprises an inner cylinder 3 centered inside an outercylinder 1 with a cylindrical gap 2 left between them. Outer cylinder 1is provided with a base 4. A piston rod 5 travels into and out of theend of the dashpot opposite base 4 through a hole at the center sealedgas-tight by packing 10. Mounted on the lower end of piston rod 5 andaccordingly traveling back and forth inside inner cylinder 3 is a piston6, the spaces at each face constituting pressure chambers 7 and 8. Acompressible-gas accommodating compartment 11 compensates for variationsin the volume of gas forced in by piston rod 5 as it travels in and out.There is a vent 12 at the base 4 of inner cylinder 3. Below vent 12 is aport 13 that opens into cylindrical gap 2. Above packing 10 are otherports 14, which open into gas-accommodating compartment 11 and allow theremoval of excess lubricant from piston rod 5.

[0035] The open ends 9 of the outer cylinder 1 and inner cylinder 3 inthe embodiment illustrated in FIG. 1 are welded together and folded in,leaving a round hole at the center to align piston rod 5 above packing10. Vent 12 is fastened to base 4 at the bottom of outer cylinder 1 byinterlocking beads and grooves. The edge of base 4 is welded to the edgeof outer cylinder 1. A depression 15 accommodates the head of a screw 16employed to adjust vent 12.

[0036]FIG. 2 illustrates a variant of the embodiment illustrated inFIG. 1. The base 4 in this version is also welded to outer cylinder 1,but merges into an inward-tapering section 17 with vent 12 mounted onits upper edge and provided with a collar 18. The section of innercylinder 3 extending above the transition between base 4 andinward-tapering section 17 is provided with ports 19. There is a similardepression 15 in base 4 to accommodate the head of a vent-adjustmentscrew 16.

[0037] The upper end of the two-cylinder dashpot, which provides accessto the piston rod, in the embodiment illustrated in FIG. 3 isconventional, and only the lower end is accordingly illustrated. Thebottom edge of outer cylinder 1 rests against the edge ofinward-tapering section 17 of inner cylinder 3, and both edges have beenmolded cold or hot around base 4 with no machining involved. Vent 12,which is fastened as in the embodiment illustrated in FIG. 2, can beintroduced along with any other components through the upper, open, endof the dashpot. Once the dashpot has been, conventionally, closed andthe cushioning and pressure-accommodating gases injected, the dashpot isfinished. Here again, as in the embodiments illustrated in FIGS. 1 and2, base 4 is provided with a depression 15.

[0038] The base 4 of the embodiment illustrated in FIG. 4 is similar tothe base 4 specified with reference to FIG. 3, although inner cylinder 3is in this case in a single part, and vent 12 must accordingly beinserted through it from above. To facilitate assembly, the lower end 20of inner cylinder 3 tapers in slightly, preventing damage to thecylinder's inner surface from the entering vent. Ports 19 are here aswell provided at the transition to lower end 20. A depression 21demarcating the bottom edge of vent 12 is punched out along with ports19.

1. Dashpot with an inner cylinder (3) accommodated in an outer cylinder(1), and a piston (6) traveling back and forth inside on the end of apiston rod (5) and separating the inner cylinder into two chambers (7 &8), whereby the piston rod enters the cylinders through a hole at oneend that seals it off and positions it, the outer cylinder is providedwith a base (4) at the end opposite the end with the hole, the innercylinder is centered along the axis of the outer cylinder at each end,and the cylindrical gap (2) between the two cylinders is provided with afluid-accommodating compartment (11) and, toward the base, a port (13)opening into the adjacent chamber (8), which accommodates, preferablyabove the port, a vent (12), characterized in that the mutuallycontacting ends of the cylinders are hot or cold welded together at thebase end or at the end remote from the base.
 2. Dashpot as in claim 1 ,characterized in that the ends of the cylinders (1 & 3) are welded to aseparate base (4).
 3. Dashpot as in claim 1 , characterized in that theends of the cylinders (1 & 3) are molded hot or cold into a base (4). 4.Dashpot as in one or more of claims 1 through 3, characterized in thatthe base (4) is provided with a short upward-and-inward tapering section(17) of approximately the same diameter as the inner cylinder (3) thatincludes a vent (12) and that the inner cylinder continues beyond. 5.Dashpot as in one or more of claims 1 through 4, characterized in thatthe inner cylinder (3) has inward-extending depressions (21) above theports (13 or 19) between the cylindrical gap (2) and the chamber (8) toaccommodate the vent (12).